The present invention relates to a method for forming loops in circular knitting machines, and particularly to a system for arranging the needles in cooperation with the sinker so that part of the loop is made by the needles and part is made by the sinker.
Conventional knitting machines employ both needles and sinkers. The sinkers are moved in a horizontal direction and their function is limited to knocking off the knit work or loops from the needle. The forming of loops is performed by drawing yarn on to the needles over the level of the sinkers, the size of the loop being determined by the depth of the drawing of the needles below the loop forming level of the sinkers. The level of the sinkers remain constant with respect to the needle cylinder and with respect to the drawing of the loop.
Since the formation of the loop and its size is solely dependent on the movement of the needle, it is necessary to take great care in controlling the movement of the needle. In operation, the needles are moved synchronously in progression to draw in the yarn and it is therefore necessary to choose the pitch angle of the needle cam so that the progression of movement (i.e., the number of simultaneously drawn in needles) does not surpass a predetermined limit at which due to high friction, the yarn tension would increase to an extent that the yarn is broken. This problem is accentuated when the speed of the machine is increased to high production levels. On the other hand by choosing a high pitch angle for the needle cam, it is possible to increase the working speed of the machine, however, this results in a great deal of mechanical stress and strain on the needles coupled with frequent failure and a large number of broken needles.
It is an object of the present invention to provide a method for operating a circular knitting machine overcoming the disadvantages and disabilities of the prior art devices.
A further object of the present invention is to provide a method for use of a circular knitting machine in which the sinkers are operated in cooperation with the needles to perform the function of not only knocking off the loop but of also forming a part of the loop in cooperation with the needles.
It is a particular object of the present invention to provide a circular knitting machine in which the sinkers are moved in an oblique angle to the path of movement of the needle so that the sinkers need only be reciprocated a relatively small extent.
It is a further object of the present invention to provide a circular knitting machine wherein both the needles and sinkers cooperate to form portions of the same loop thereby enabling the machine to be made with fewer needles.
These objects, others and numerous advantages will be found clearly set forth in the following specification of the present invention.